pixel

Method that processes pixels in a certain way

本小妞迷上赌 提交于 2019-12-06 11:37:36
in a code snippet, I have found the following method that I could not understand: static void processPixels(int width, int height, int *pixels, int *rgb) { int R[256]; int G[256]; int B[256]; for (int i = 0; i < 256; i++) { R[i] = (rgb[i] << 16) & 0x00FF0000; G[i] = (rgb[i] << 8) & 0x0000FF00; B[i] = rgb[i] & 0x000000FF; } for (int i = 0; i < width * height; i++) { pixels[i] = (0xFF000000 & pixels[i]) | (R[(pixels[i] >> 16) & 0xFF]) | (G[(pixels[i] >> 8) & 0xFF]) | (B[pixels[i] & 0xFF]); } } Can somebody explain what the purpose of those shiftings are ? Are they extracting sth. ? And what is

html5 canvas: clipping by color

感情迁移 提交于 2019-12-06 09:53:42
问题 is there any way to choose an area on the canvas by color and clip it? I want to be able to clip an undefined aread that the only thing in common between all the pixels is that they all have the same color. thanks 回答1: Live Demo Below is a way to select a color.. and do whatever you want with it. I pass a color I want to find iterate over every pixel and remove the color that matches, since Im not sure what you meant by clipping I assumed you mean remove. However please note on large images

Calculating pixel length of an image

北慕城南 提交于 2019-12-06 08:35:14
问题 May I know what are the ways to calculate the length of 1 pixel in centimeters? The images that I have are 640x480. I would like to compare 2 pixels at different places on the image and find the difference in distance. Thus I would need to find out what's the length of the pixel in centimeters. Thank you. 回答1: A pixel is a relative unit of measure, it does not have an absolute size. Edit . With regard to your edit: again, you can only calculate the distance between two pixels in an image in

C# - Converting 8-bit or 16-bit grayscale raw pixel data

半世苍凉 提交于 2019-12-06 07:08:09
问题 I need to be able to convert 8-bit or 16-bit grayscale pixel data into a file format that the .NET framework can support. The data I have available is the width, height, orientation (bottom-left) and the pixel format as 4096 shades of gray (12-bit resolution) packed in 2 bytes per pixel. So for example each pixel ranges from 0 to 4096, and each pixel is 2 bytes. I have already tried using PixelFormat.Format16bppGrayScale with the Bitmap constructor, and it throws a GDI+ exception. Everything

高德地图基础

白昼怎懂夜的黑 提交于 2019-12-06 06:22:40
一,基础类: new AMap.Pixel(x:Number,y:Number)  构造一个像素坐标对象。,确定地图上的一个像素点。xy为像素单位 new AMap.Size(width:Number,height:Number)   地物对象的像素尺寸  构造尺寸对象。参数width:宽度,height:长度,单位:像素; new AMap.LngLat(lng:Number,lat:Number,noAutofix:bool)  经纬度坐标,确定地图上的一个点。 lng、lat分别代表经度、纬度值; noAutoFix表示是否自动将经度修正到 [-180,180] 区间内,缺省为false, new AMap.Bound( southWest: LngLat , northEast: LngLat )  地物对象的经纬度矩形范围。参数southWest、northEast分别代表地物对象西南角经纬度和东北角经纬度值。 二,地图: new AMap.Map( container:String/HTMLDivElement, opts: MapOptions ) 方法: getBounds( )  获取当前地图视图范围,获取当前可视区域。 getSize( )    获取地图容器像素大小 setZoom(level:Number)  设置地图显示的缩放级别,在PC上

Converting PNG file to bitmap array in Python

时间秒杀一切 提交于 2019-12-06 06:01:23
I would like to convert a PNG image to a 2 dimensional array where each array holds a list of the RGB values of that specific pixel. How could one create a program to read-in a *.png file and convert to this type of data structure? If you have PIL installed then you can create an image with Image.open and get the colors like so: data = [image.getpixel((x, y)) for x in range(image.width) for y in range(image.height)] You can use the existing pygame module. Import a file into a Surface using pygame.image.load . You can then access the bit array from this using pygame.surfarray.array2d . Please

How to measure object size in real world in terms of measurement like inches centimeters etc from object size in the image in pixels?

微笑、不失礼 提交于 2019-12-06 05:43:41
问题 I have calculated object size in terms of pixel from the image containing object. I want to measure object size in real world. Is there any way to find out multiplying factor to measure actual size ? I'm currently using python for implementation. 回答1: Typically you will have obtained your image with a camera which projects the 3 dimensional scene onto a 2 dimensional sensor by means of a lens. The vertical (height) projection is represented in the following diagram ( I am assuming a

Dynamically pixelate an html image element

人走茶凉 提交于 2019-12-06 04:44:58
问题 I'm to take an image on a webpage, and then use javascript (or whatever would be best suited) to dynamically 'pixelate' it (e.g. into 20px squares). Then, as the user scrolls down the page, I need the image to gradually increase in resolution, till it is no longer pixelated. Any ideas how I could go about doing this? I realise I could use php to resize an image and several times and just switch out the image, but that would require loading several extra images. Also, I know I could probably

Web Layouts: pixels vs percentages

北慕城南 提交于 2019-12-06 04:37:47
问题 What are the use cases for defining distances in a web layout for pixels and percentages? Is there any downside to using pixels with respect to multiple resolutions? Will they scale correctly? 回答1: Percentage layout This is generally referred to as fluid layout. Your elements will take a defined percentage of the total space available to them. This available space is determined by the element's parent. When using percentage layouts, it's a good idea to specify a min-width and max-width on

建议收藏备用:.net core使用QRCoder生成普通二维码和带Logo的二维码详细使用教程,源码已更新至开源模板

你离开我真会死。 提交于 2019-12-06 04:20:19
原文: 建议收藏备用:.net core使用QRCoder生成普通二维码和带Logo的二维码详细使用教程,源码已更新至开源模板 随着互联网越来越生活化,二维码的使用越来越普遍,不论是扫码支付还是扫码关注引流,似乎我们总是离不开二维码,那么很多需要推广的文章或社区想要自己的二维码,那么你是不是需要在网站直接提供给用户呢?很多开发者就在网上百度解决方案,边做边踩坑,甚至很多人写的开发案例都是截图或者类库引用都没说清楚,在这个摸索的途中造成很多时间上的浪费。 尤其是尝试新技术那些旧的操作还会有所改变,为了节约开发时间,我们把解决方案收入到一个个demo中,方便以后即拿即用。而且这些demo有博客文档支持,帮助任何人非常容易上手开发 跨平台的.net core 。随着时间的推移,我们的demo库会日益强大请及时 收藏 GitHub 。 一、首先在Common公用项目中引用QRCoder类库 Install-Package QRCoder -Version 1.3.3 二、 在Common公用项目中创建 QRCoderHelper类 #region 普通二维码 /// <summary> /// /// </summary> /// <param name="url">存储内容</param> /// <param name="pixel">像素大小</param> /// <returns